Shrub/tree for a very large pot?

i've just invested in a really big black pot for my patio. The pot is quite contemporary looking and will be in full sun (against a south facing fence)

I'd like something striking to grow in it but having combed through my gardening books am not feeling very inspired! The plant needs a fair amount of height to be make an impact over the top of the table and chairs. It will get quite hot in the height of summer but this is a rural area so chilly in the winter.

The fence has jasmine and clematis already growing up it and there is a bamboo in a nearby bed too. Nearby planting is in fairly hot colours with some white flowers.

I can really recommend Heptacodium miconioides. It 's a large shrub or small tree with lovely white flowers from late summer to late autumn. Also named Seven son flower tree. After the real flowers have gone there is still an impression of flowers as the coloured sepals stay on for a long time. Very beautiful and not very well known at all, which is a shame IMO. It seems I can't put a link in but if you google for it there is lots of information to find.